SiCp/Al复合材料电阻点焊剪切断口形貌

摘要

To optimize the resistance spot welding parameters of SiCp/A1 composite, the composite was bonded by resistance spot welding（RSW） at different welding currents and welding times, and the shear strength test of the RSW joint was carried out. The morphologies of different RSW shear fractures were observed by SEM. The results show that when the welding current,welding time and the electrode pressure equals to 14.6 kA,0.2 s and 2 500 N respectively, the RSW joint has the highest strength and the value can reach 1 693 N. The mor- phologies of the two side of the joint shear fracture are round boss and circular hole respectively ,which is typi- cally a button fracture, and the RSW joint was well welded. The welding current and the welding time must match each other. When the matching value is lower than the optimum parameter, only a few points form metal- lurgical bonding on the RSW joint surface, which is a typical bonding surface fracture and the joint strength is relatively low. When the matching valve is higher than the optimum parameter, the RSW joint can be overhea- ted easily, so that the RSW joint surface appears adhesion to low joint strength and the fracture has cracking, porosity and spatter defect.%为了优化SiC p/Al复合材料电阻点焊工艺参数,采用不同焊接电流和焊接时间对SiCp/Al复合材料进行了电阻点焊连接,对接头进行了剪切强度试验,用扫描电镜对不同的点焊剪切断口进行微观形貌分析.结果表明：最优的焊接电流和时间匹配值为焊接电流I=14.6 kA,焊接时间t=0.2 s,配合电极压力F=2 500 N点焊,熔核直径适中,接头拉剪力可达1 693 N;撕开后的焊点断口两侧分别呈规则的圆凸台和圆孔状,呈纽扣型断裂,接头成型良好.当焊接电流和时间的匹配值小于最优参数时,点焊接头只有少量的点形成冶金结合,呈结合面断裂,焊接强度较低;当焊接电流和时间的匹配值大于最优参数时,点焊接头易过热,断口上出现气孔、裂纹、电极粘附烧蚀缺陷,接头强度降低.